Glutamic acid acts as a neurotransmitter in the central nervous system of mammals, and controls the activity of neurocytes or the release of neurotransmitters via a glutamate receptor existing in synapses. At present, a glutamate receptor is classified into an ionotropic receptor and a metabotropic receptor from many pharmacological and physiological studies (Hollmann M. and Heinemann S., Annu. Rev. Neurosci., 17 (1994) 31-108). An NMDA (N-methyl-D-aspartic acid) receptor is an ionotropic glutamate receptor specifically sensitive to the NMDA as an agonist (Moriyoshi K., Nature, 354 (1991) 31-37; Meguro H., Nature, 357 (1992) 70-74); and has high Ca2+ ion permeability (Iino M., J. Physiol., 424 (1990) 151-165). The NMDA receptor is expressed with a specific pattern in the central nervous system (Ozawa S., Prog. Neurobiol., 54 (1998) 581-618).
From many pharmacological and biological studies, it is believed that an NMDA receptor is involved in higher nerve activities such as memory, learning, and the like (Morris R. G., Nature, 319 (1986) 774-776; Tsien J. Z., Cell, 87 (1996) 1327-1338). On the other hand, it is suggested that the acute or chronic enhancement or inhibition of the NMDA receptor activity relates to various nervous system diseases, for example, ischemic apoplexy, hemorrhagic brain disorder, traumatic brain disorder, neurodegenerative disorders (Alzheimer's disease, cerebrovascular dementia, Parkinson's disease, Huntington's disease, amyotrophic lateral sclerosis, and the like), glaucoma, AIDS encephalopathy, dependence, schizophrenia, depression, mania, stress-related diseases, epilepsy, pain, and the like (Beal M. F., FASEB J., 6 (1992) 3338-3344; Heresco-Levy U. and Javitt D. C., Euro. Neuropsychopharmacol., 8 (1998) 141-152; Hewitt D. J., Clin. J. Pain, 16 (2000) S73-79). Accordingly, it is thought that drugs capable of controlling the activity of an NMDA receptor would be extremely useful in clinical application.
As drugs capable of controlling the activity of an NMDA receptor, a large number of non-competitive NMDA receptor antagonists are reported, but many of them have not been used in clinical application because of their side effects based on the NMDA receptor-antagonizing effect thereof, for example, mental aberrations such as hallucinations and confusion, giddiness and the like. It has been tried to apply some of the conventional NMDA receptor antagonists, for example, ketamine and dextromethorphan, against pain or the like in clinical application (Fisher K., J. Pain Symptom Manage., 20 (2000) 358-373). However, their safety margin in treatments is narrow, and their clinical use is limited (Fide P. K., Pain, 58 (1994) 347-354). Also, memantine is known as a non-competitive NMDA receptor antagonist that has comparatively few side effects (Parsons C. G., Neuropharmacol., 38 (1999) 735-767); and recently, it has been reported that it is effective for Alzheimer's disease (Reisberg B., N. Engl. J. Med., 348 (2003) 1333-1341). However, the safety margin of memantine as a medicine is still not satisfactory, and development of an NMDA receptor antagonist having a broader safety margin is desired (Ditzler K., Arzneimittelforschung, 41 (1991) 773-780; Maier C., Pain, 103 (2003) 277-283; Riederer P., Lancet, 338 (1991) 1022-1023). It is expected that creation of such an NMDA receptor antagonist superior in terms of a broader safety margin may bring about new clinical usefulness of the NMDA receptor antagonist.
It is known that a cyclic amine derivative represented by the following formula has an NMDA receptor antagonistic action and is useful for treating and preventing Alzheimer's disease, cerebrovascular dementia, Parkinson's disease, ischemic apoplexy, or pain (Patent Document 1). However, this document neither discloses nor suggests the fused indane compound according to the present invention.

(For the symbols in the formula, refer to this document).
Further, it is known that a compound represented by the following formula has anticancer activities (Patent Document 2). However, there is neither disclosure nor suggestion on its NMDA receptor antagonistic action, nor its usefulness for treating Alzheimer's disease, cerebrovascular dementia, Parkinson's disease, ischemic apoplexy, pain, or the like according to the present invention.

Furthermore, it is suggested that a compound represented by the following formula is a ligand for a dopamine D3 receptor and relates to the diseases regarding central nerves (Non-Patent Document 1). However, this document neither discloses nor suggests the fused indane compound according to the present invention.

Further, an indeno[1,2-b]pyridine compound in which a phenyl group is substituted at the 9b-position is known as a ligand for NK-1 and dopamine receptors (Non-Patent Document 2 and Non-Patent Document 3). However, this document neither discloses nor suggests the fused indane compound according to the present invention.
In addition, an indeno[1,2-b]pyridine compound in which a phenyl group is substituted at the 5-position is known (Non-Patent Document 4). However, this document neither discloses nor suggests the fused indane compound according to the present invention.
Also, it is suggested that a compound represented by the following formula has a catecholamine uptake inhibitory action and can be used as an anti-depressant or an anti-Parkinson's disease drug (Non-Patent Document 5). However, this document neither discloses nor suggests the fused indane compound according to the present invention.

(In the formula, R represents —H or methyl).
Furthermore, two compounds below are known on the database as CAS registry numbers 1220-39-9 and 97555-62-9.
    [Patent Document 1] Pamphlet of International Patent Publication WO 2006/033318    [Patent Document 2] Pamphlet of International Patent Publication WO 2006/094602    [Non-Patent Document 1] ChemBioChem, 2004, Vol. 5, No. 4, pp. 508-518    [Non-Patent Document 2] Tetrahedron, 2002, Vol. 58, No. 21, pp. 4225-4236    [Non-Patent Document 3] Tetrahedron Letters, 2001, Vol. 42, No. 29, pp. 4919-4922    [Non-Patent Document 4] Journal of Computational Chemistry, 1993, Vol. 14, No. 8, pp. 934-943    [Non-Patent Document 5] Quantitative Structure-Activity Relationships, 1991, Vol. 10, No. 2, pp. 118-125